糖尿病肾病（DN）的发病机制未完全阐明，肾小管上皮细胞转分化（EMT）与DN密切相关。circRNA为一种新的调控miRNA功能的RNA分子，广泛参与了多种疾病的发病过程。我们前期研究发现： circRNA_0013372在DN肾脏组织中的表达降低，而miR-21表达升高；miR-21可能是circRNA_0013372的潜在靶点；miR-21过表达能下调Smad7。故推测circRNA_0013372可能通过下调miR-21参与EMT。因此，本课题针对DN发病的中心环节—EMT，以miR-21-Smad为切入点，以circRNA_0013372为研究靶点。采用FISH、RT-PCR、WB、细胞转染、荧光素酶报告基因，进一步阐明circRNA_0013372-miR-21-Smad7轴在EMT发病机制，为将来研发以circRNA为靶点的防治DN药物提供理论依据。

The pathogenesis ofdiabetic nephropathy(DN) has not been fully elucidated.Epithelial-to-mesenchymal transition (EMT) is closely related to diabetic nephropathy (DN). CircRNA was as a new RNA molecules with regulation of miRNA function, widely involved in the disease process of many diseases. Our preliminary experiments showed that there was the decrease of circRNA_0013372 expression and the increase of miR-21 in kidney tissues with DN. miR-2 1may be circRNA_0013372 potential targets. miR-21 overexpression decreased smad7 expression. Hereby, we speculated that circRNA_0013372 may be involved in the EMT by downregulating miR-21. In this study, EMT was as a center-link of DN, miR-21-smad7 was as the key breakthrough point, circRNA_0013372 was as a research targets. FISH, RT-PCR, cell transfection, luciferase reporter gene assays, WB and confocal microscope were used, respectively. This study will further elucidate the pathogenesis of circRNA_0013372-miR-21-Smad7 axis in the EMT，and provide theoretical basis for the prevention and treatment of DN with circRNA-targets drugs in the future.